A method for shimming a magnetic field in a magnetic resonance tomography (MRT) device includes determining a field of view region for an object under examination. Determining the field of view region includes adapting the field of view region automatically to a region of the object under examination to be examined by the MRT device. Before the MRT device records an image, an adjustment measurement of the magnetic field is performed. A field map of the magnetic field of the field of view region is defined based on the adjustment measurement. A shimming of the magnetic field is implemented based on the field map.